The CAS Registry Mumber 74190-45-7 includes 8 digits separated into 3 groups by hyphens. The first part of the number,starting from the left, has 5 digits, 7,4,1,9 and 0 respectively; the second part has 2 digits, 4 and 5 respectively. Calculate Digit Verification of CAS Registry Number 74190-45: (7*7)+(6*4)+(5*1)+(4*9)+(3*0)+(2*4)+(1*5)=127 127 % 10 = 7 So 74190-45-7 is a valid CAS Registry Number.